Metallics JMTLN10SS Nut M10 Hex Kep Lock Nut 18-8 SS (Jar 100)

The nut body is 18-8 stainless steel, the standard austenitic grade used for general corrosion resistance. That makes it suitable for damp and outdoor work. For salt spray or coastal exposure, buyers typically step up to 316 stainless.

A kep nut (also called a K-lock) has a free-spinning external-tooth lock washer already captured on the bearing face. Tightening bites the washer teeth into the mating surface, which resists loosening from vibration. No separate lock washer needed, so it's one piece to handle instead of two on panel and enclosure work.

It ships as a jar of 100 nuts, which is the usual shop or service-truck pack for electrical fasteners. If you're standardizing on M10 hardware across a building, order by jar count rather than by piece.

Use the kep nut where you want a thin, fast-driving vibration-resistant nut that bears on sheet metal or a panel face and needs no washer. A nylon insert (nyloc) nut locks on the thread instead of the surface, holds better when the joint isn't fully torqued down, and is the usual pick where heat is low and the nut won't bear on painted or finished surfaces. The kep's teeth will score a finished face.

Kep nuts are generally treated as one-time-use. Once the washer teeth have bitten into the mating surface the locking action is reduced on reinstallation. Because the jar carries 100 pieces, most crews just fit fresh ones on reassembly.

Stainless on stainless can gall, and 18-8 is prone to it when run down fast or dry. Thread the nut slowly with a wrench rather than an impact, and use an anti-seize compound on longer stud runs. Pairing with a plated steel bolt avoids the issue but gives up the full corrosion benefit.

It's a hex-pattern nut, so it drives with a standard open-end, box, or socket wrench, not a specialty tool. Metric sockets are required since the nut is M10 rather than an inch size.